US2897704A - Predetermined torque release, ratchet-type wrench - Google Patents

Description

2 Sheets-Sheet 1 fg.

IN V EN TOR ,4free/ves@ R. G` WOODS PREDETERMINED TORQUE RELEASE, RATCHET-TYPE WRENCH Filed July 19, 1957 R. G. WOODSI Aug. 4, 1959 PREDETERMINED TORQUE RELEASE, RATCHET-TYPE WRENCH Filed July 19, 1957 PREDETERMHNED TORQUE RELEASE, RATCHET-TYPE WRENCH Robert Glen Woods, Huntington Park, Calif.

Application `llully A19, 1957, Serial No. 673,064

15 Claims. (Cl. 81--52.4)

The present invention relates generally to the field of wrenches and more particularly to an improved form of predetermined torque release, ratchet-type wrench.

Adjustable torque wrenches of the spring loaded type are well-known in the prior art. In general, such wrenches include a load-engaging member, a lever for applying torque to the load, and spring loaded means that connect the load-engaging member and lever for rotation in unison. When excessive torque is applied to the wrench, the spring loaded means is momentarily overcome to permit limited movement of the lever relative to the load-engaging member. Such relative movement can, of course, be felt by the user and is normally also accompanied by an audible knock, thus indicating that the desired amount of force has been applied to the load.

In devices of this class, helical springs or circular springs can be used for smaller wrenches but the use of `such springs in large wrenches requires a large circular cross-sectional area for the lever and handle. In order `to have a handle that is small enough for convenient use,

it is desirable to use spring means of a configuration that will provide the force required for large torque wrenches and yet be small enough to be contained in a small cavity. Moreover, helical or circular springs do not conform to the flat or rectangular cross-section of wrench which is apparently preferred by mechanics rand it is ktherefore desirableto provide spring means adapted to fit a rectangular cross-section lever.

An object of my invention is to provide an adjustable torque wrench having improved spring means adapted to be contained in a cavity of minimum cross-sectional area and capable of meeting the load requirements of large or small torque wrenches.

A further object of the invention is to provide spring means for a torque wrench comprising a plurality of individual springs that permit a wrench to be quickly and easily calibrated in the manufacture thereof.

Another object of my invention is to provide a torque wrench that has a ratchet drive on an axis common to the load-engaging member and the pivotal connection of the lever. With this arrangement the wrench retains the geometry of a simple lever, whereby it can easily be calibrated for accurate operation and can be grasped for use at any point along its handle.

Another object of my invention is to furnish an adjustable torque wrench which has reversible pawl and ratchet means, whereby torque can be applied to the load in either direction and without lifting the wrench from the load.

1t is also an object of the invention to make available a device of this type which visibly breaks when a predetermined force is applied thereto and that can be calibrated to break at the same or different forces in clockwise and counterclockwise directions or rotation.

A further object of the invention is to provide an adjustable ltorque wrench having novel means of calibration which eliminatesmany close-tolerance machined parts 2,597,754 Patented Aug. 4, 1959 so that the wrench is extremely accurate although economical of construction.

An additional object of the invention is to provide an adjustable torque wrench which is simple of design and rugged of construction, whereby it afforts a long and useful service life.

These and other objects and advantages of the present invention will become apparent from the following description of a preferred form and certain variations thereof when taken in conjunction with the appended drawings wherein:

Figure -1 is a bottom view, partly broken away, of a preferred embodiment of my invention;

Figure 2 is a partial vertical sectional view taken on the line 2 2 of Figure l;

Figure 3 is a fragmentary view, similar to Figure l, showing parts of the wrench disposed in a different position;

Figure 4 is a partial, horizontal sectional view showing inphantom line the manner in which the wrench breaks when subjected to a predetermined torque;

Figure 5 is a View similar to Figure 4 showing the Acalibration means of a modified form of the invention;

Figure 6 is a View similar t0 Figure 4 showing a second alternate form of the invention;

Figure 7 is a view similar to Figure 4 showing still another form of my invention;

Figure 8 is a transverse sectional view taken on the line 8 8 of Figure 7;

Figure 9 is a partial horizontal sectional view showing an alternate form of spring means for use in the invention; and

Figure 10 is a view similar to Figure 9 showing another method of arranging the alternate form of spring means.

Referring to the drawings for the general arrangement of the invention and in particular to Figures l, 2 and 4, it can be seen that my improved wrench includes a load-engaging member 10 journaled in a head 12. Formed integrally with head 12 is an arm 14 which extends rearwardly from the front end of the wrench overload-engaging member 10. The arm 14 is loosely received within one end of a lever 16 which is pivotally connected thereto on the same axis as that of member 10. Head 12 and member 10 are drivingly connected by reversible ratchet and pawl means 18 so that torque -can be applied to said member in clockwise or counterclockwise direction.

Spring loaded means 20 (to be fully described later) are disposed in the lever 16 rearwardly of arm 14 and normally maintain said arm and lever in alignment so that when a turning force is applied to the outer end of lever 16, arm 14 will move in unison therewith. The force exerted by spring loaded means 20 can be adjusted so that when any excessive force is applied to .the wrench, such force momentarily overcomes spring loaded means 20 so that the wrench breaks, i.e. lever 16 pivots relative to arm 14, audibly and palpably. Upon breaking of the wrench, the user stops turning it so that excessive torque will not be applied to the bolt or nut comprising the load borne by member 10.

More particularly, referring to Figures l and 2, the head 12 is formed with a bore 24 that rotatably receives the inner end of load-engaging member 10. The normall-y lower side of head 12 has an enlarged circular opening 26 that is concentrically related to bore 24. The opening 26 serves to house a ratchet wheel 28 which in `turn is concentrically, rigidly mounted on load-engaging seen in Figures 1 and 3 and includes a rearwardly extending lug 34 that can be moved to the left or right, as desired, to cause said pawl to drivingly engage the ratchet wheel 28 for either clockwise or counterclockwise revolution.

Through the rear end of head 12 is a transverse bore 36 that at its center communicates with the rear of smaller opening 30. Slidably mounted in bore 36 is an elongate ratchet control pin 38 whose ends protrude outwardly from the sides of head 12 so that nger pressure thereon will cause sliding movement of the pin. Near one end of pin 38 are a pair of adjacent V-shaped inner and outer notches 40 and 42, respectively, that face a spring pocket 44 formed in the wall of bore 36. Pocket 44 receives a compressed helical spring 46 that at all times urges a ball 48 into one of the notches of pin 38. At its center, pin 38 has a bore 50 which receives lug 34 of pawl 32.

Axed to the lower face of head 12, by screws 94 or the like, is a cover 96 that protects the ratchet and pawl means. This cover is provided with a bore 98 through which the lug end of member protrudes.

When the ratchet and pawl means just described are in the position of Figure 1 they will drive load-engaging member 10 in clockwise direction. Spring loaded ball 48 is seated in the bottom of inner notch 40 and so yieldably maintains pin 38 in axially immovable condition with its center bore positioned to the left of the center of head 12. Pawl 32 is accordingly eccentrically disposed so that it wedgingly engages teeth of ratchet wheel 28 so long as the wrench is moved in clockwise direction. It will be noted that a pair of stop elements 52 are formed on opposite sides of pawl 32 which are adapted to abut a side portion of pin 38 to exactly position said pawl in wedging relation between ratchet wheel 28 and pin 38.

When the ratchet and pawl means are in the position of Figure 3, load-engaging member 10 and ratchet wheel 28 remain stationary while the head of the wrench is moved in counterclockwise direction preparatory to another turn of the load on the wrench. As is apparent, reversing the direction of the wrench removes the wedging force on pawl 32. Although spring loaded ball 48, through pin 38, continues to urge the pawl into wedging position, it yields to permit two-way sliding movement of pin 38 as pawl 32 is moved around wheel 28 in counterclockwise direction.

As is obvious from the foregoing description, ratchet and pawl means 18 can be reversed to drive load-engaging member 10 in counterclockwise direction merely by sliding pin 38 inwardly until ball 48 seats in outer notch 42.

As has previously been noted, arm 14 is formed integrally with head 12 and as can be seen in Figure 2, is spaced above said head. Arm 14 is substantially rectangular in cross-section and extends rearwardly from the front of the head and over load engaging member 10. The purpose of this arrangement will later become apparent.

Lever 16 is an elongate hollow member of substantially rectangular cross-section. As can be seen in Figure 4, the lever is appreciably wider than arm 14 but, as can be seen in Figure 2, slidably receives the thickness of arm 14. At its forward and along its longitudinal centerline, lever 16 is pivotally connected to arm 14 by means of a hinge pin 54, or the like. It will be noted that pin S4 is coaxially aligned with the axis of load engaging member 10. Arm 14 is substantially fully enclosed by lever 16 and as is obvious, the lever is capable of only limited pivotal movement relative to the arm, due to the length of arm 14.

Axially slidably mounted on lever 16 is a circular handle support 56, which can be seen in Figure 2. Support 56 is formed with an annular lip 58 that matingly engages a complementary annular groove 62 formed on the interior surface of a cylindrical handle 60. Handle 60 is thus rotatably supported at its front end on lever 16. This handle includes a rear wall 64 that rigidly supports an interiorly disposed axially extending rod 66. The rod 66 is formed with threads that matingly engage a tapped bore 68 in the center of a cap 70 rigidly atixed to the rear end of lever 16.

Enclosed within lever 16 between arm 14 and rod 66 are springs 72, a movable plunger 74 and a camming block 20. As is apparent, rotation of handle 60 on lever 16 will simultaneously effect compression or expansion of springs 72 as handle 60 moves axially. By this means, the compressive force of springs 72 can be adjusted at will to control the amount of torque at which the wrench will break, in a manner presently to be set forth.

On its free end, rod 66 is provided with a pad 76 that abuts the rear end of springs 72. Block 20 is interposed between the rear end of arm 14, which acts as a relatively fixed abutment, and the front end of plunger 74. Under urging of the springs 72, plunger 74 forcefully urges block 20 against arm 14.

Block 20 is substantially cubical and should be accurately machined. In order for the wrench to be accurately calibrated, the block 20 must be centered on the longitudinal centerline of lever 16 where it serves to normally maintain said lever in alignment with arm 14. Accordingly, the front end of block 20 is received in a depression 78 formed in the center of the rear face of arm 14 while its rear end is received in a depression 80 formed in the center of the forward face of plunger 74. Each of said depressions has sloping sides to receive an end of block 20 and the bottoms of said depressions are of the same width as the block so that its ends are snugly buttressed between arm 14 and plunger 74.

For any given set of springs 72, the wrench can be calibrated merely by selecting the proper length of block 20. If exactly the same length is given to each side of the block, the wrench will break at the same amount of torque whether moved to the left or right. It it is desired for any particular application to have the wrench break at diierent amounts of torque according to the direction in which used, the wedging angle between the adjacent ends of arm 14 and plunger 74 can be changed by merely making block 20 longer on one side than the' other.

As is apparent, arm 14, plunger 74 and lever 16 could be round rather than rectangular in cross-section. However, a rectangular cross-section form of construction is used to adapt the wrench for the special form of springs incorporated therein. Accordingly, plunger 74 is substantially rectangular and of such thickness as to be easily slidably received between the upper and lower walls of lever 16. On each of its sides, plunger 74 has a pair of roller bearings 82 to reduce the friction of its contact with the side walls of lever 16.

It will be observed that the bearings 82 provide a slight clearance space between the side walls of lever 16 and plunger 74. Thus, when the wrench breaks and plunger 74 moves rearwardly to `compress the air in handle 60, the air pressure can bleed off in this space without aiecting the accuracy of the wrench. I have found that in some instances it is desirable to provide a central bore longitudinally through plunger 74 that opens when block 20 cams away from the end of the bore during breaking of the wrench, to immediately vent to the atmosphere the air space inside of handle 60.

Springs 72 comprise a plurality of pairs of spring members in abutting series. Each spring includes a Hat center section 84 and a pair of outwardly offset sides 86. As lcan been seen in Figure 4, springs 72 are arranged in pairs so that each spring contacts the other of a pair at the outer ends thereof and each pair contacts another pair at center sections thereof. As many individual springs or pairs may be used as desired to calibrate the wrench.

In order to provide a visual indication of the breaking point at which the wrench is set, the front edge of the handle y60 has integral, annularly spaced index mark- 'ings 88. Complementary scale markings 90 are formed on the lower or upper wall of lever 16. These markings are graduated in ft.lbs. and are coordinated with the spring rate of springs '72 to control the breaking point of the wrench.

In operation, before a bolt or nut tightening operation is started, handle 60 is rotated on lever 16 until the markings 88 and 90 are set at the desired reading. The correct size of socket or other work holding means is then placed on member 10 to engage its lug 92 and the work piece then placed in the socket. After ratchet and pawl means 18 have been set for the desired clockwise or counterclockwise tightening movement of the wrench, force is applied to handle 60. Due to the wedging action of pawl 32, torque will be applied to member 10 and its load. As long as the load remains under the ft.-lb. setting of the wrench, pivotal movement of lever 16 relative to arm `14, i.e. breaking will be resisted by the force of springs v72. Upon such Ivalue being reached, the spring loading on block 20 will momentarily be overcome when block 20 is wedgingly canted to cam plunger 74 rearwardly. The wrench then breaks with an audible sound, thus providing visual, aural and palpable indications that the desired degree of tightening of the nut or bolt has been achieved.

The placement of the ratchet and pawl means 18 in vhead 12 should be particularly noted. This arrangement permits the inclusion of a ratchet drive in an adjustable torque wrench without complicating its geometry or affecting the calibration of the spring-loaded breakings means. It will be seen that in this structure the lever 16, ratchet and pawl means 18 and load-engaging member 10 all have a common axis rather than having laterally spaced apart separate axes. Accordingly, for any given force applied at any point along the handle of the wrench, the same `amount of torque will result at hinge pin 54v and member 10. On the other hand, if the hinge pin 54 and member 10 had separate axes, the result would be a compound lever having different torque 'values at. each axis. Obviously, the geometry of a compound lever adjustable torque wrench would make such a device more)` difficult to calibrate. The present invention, even though it includes a ratchet drive, retains the simplicity of a simple lever.

Figure shows an alternate form of cam adjustment means for calibrating the invention. In this form the wedging angle between adjacent ends of the arm and plunger can be changed by cam adjustment means that eliminate close tolerance machining of parts.

In the alternate form, calibration of the compressive: force of springs 72 can be accomplished, as before, by' controlling the length of block 20. However, calibration to permit the wrench to be set to break at the same value, whether used in clockwise or counterclockwise direction, is accomplished by means of an adjustable arm 14.

The arm 1d is composed of two sections, a fixed section 100 and a mating longitudinally slidable section 102. The latter section at its rearward end comprises substantially half the width of arm 14 and at its forward end. is of reduced width to define a shoulder d therein which faces a complementary shoulder 106 formed in section 100.

A longitudinally extending counterbore 108 extends from the forward end of section 100 to open into shoulvder 106. The inner end of counterbore 108 is of reduced diameter and interiorly threaded to receive the threaded stem of an adjustment screw 110. The inner end of the screw 110 abuts shoulder 104. When the screw is turned inwardly, the section 102 is forced rearwardly to ad just it longitudinally relative to fixed section 100.

The position vof slidable section 102 relative to fixed section 100 is maintained by a pair of set screws 112. The set screws are longitudinally spaced in fixed section 100 to ride in longitudinally extending slots 114 formed in slidable section 102. A countersink 116 is superim-` posed on each slot 114 to receive the enlarged head of each set screw. After slidable section 102 has been moved rearwardly the desired amount by adjustment screw 110, it can be securely fastened in place by tightening set screws 112.

Block 20 is buttressed between a depression 7S formed in the rear face of arm 14 and a depression 80 formed in the forward face of a plunger 74'. As will presently appear, the construction of the arm 14 with slidable sec= tion 102 as a part thereof, permits canting block 20 to the left or right.

Depression 7 8 is defined by the rear ends of fixed section 100 and slidable section 102. Each of the two sides of depression 78 is defined by a pair of sloping walls 4whose common corner 118 snugly receives a front edge of block 20. The two corners 118 are normally spaced apart the same distance as the width of block 20. The depression 80 is like depression 80 of the previously described embodiment of the invention.

With the form of the invention shown in Figures 1-4, in order for the wrench to have the same breaking point in both clockwise and counterclockwise directions, it is essential that arm 14 and lever 16 have the same longitudinal centerline and that the rivet 54 and the camrning block 20 be centered on said centerline. In addition, the block 20 must be of exactly the same length on both sides. If different breaking points in clockwise and counterclockwise directions are desired, block 20 must have its sides of different lengths. Obviously, this construction, while highly eiiicient, requires the parts to be dimensionally accurate and precisely located.

The alternate form of calibration means just described eliminates much close tolerance machining. The same block 20', having the same length on both sides, is used when the clockwise and counterclockwise breaking points are to be the same or different from one another. It will be seen from Figure 5 that longitudinal adjustment of sliding section 102 can cause canting of spring loaded block 20 to left or right, as desired. Such adjustment, in effect, alters the wedging angle between theendsof arm 14 and plunger 74 by controlling the longitudinal alignment of lever 16 and the arm 14. Thus, if it is desired to have the same breaking point in both directions, arm 14 and lever 16 should have the same longitudinal centerline. Block 20 will then have its front edges seated in corners 118 of depression 78 and since the sides of the block are of the same length, the wedging angle between the ends of arm 14 and plunger 74 `will be the same in both clockwise and counterclockwise directions.

If any of the parts of the device are not accurately finished, the wrench can nevertheless be accurately calibrated to break at the same point in both directions merely by adjusting slidable section 102. So too, if it is desired to calibrate the wrench for different breaking points, such adjustment will accomplish the desired difference.

As is apparent, movement of slidable section 102 from its position of Figure 5 will cant block 20' to the left or right. The front edges of the block will then no longer be seated in corners 118 but will be wedgingly engaged by the sides of depression 78. Lever 16 will therefore be moved pivotally relative to arm 14', thus increasing or decreasing the wedging angle to left or right.

Figure 6 shows a second alternate form of calibration or cam adjustment means. This form is the same as the first alternate form in principle, but employs a different type of block. While limited differences in clockwise and counterclockwise breaking points are possible with the -arrangement used in the first alternate form, the primary purpose of that arrangement is to provide a means of calibration for the same breaking point in both directions, despite inaccuracies in machining.

The second alternate form employs a block 20 of a configuration that permits greater differences between clockwise and counterclockwise breaking points. This block is adapted to be supported between a narrow depression 80 in the forward face of a plunger 74 and a wider depression 78 formed in the rear face of an arm arm 14". Block 20 is generally Y-shaped and has an integrally formed, rearwardly extending center rib 120. The rib 120, along its opposite edges, is wedgingly received in the narrow depression 80, whose bottom is narrower than the rib.

The arm 14" of the second alternate form is exactly like the arm 14 of the first alternate form except for the configuration of depression 78". As Figure 6 shows, depression 78'l is rectangular in plan view, being defined between rearwardly extending fingers 124 that are oppositely disposed on the sides of arm 14". The block 20 is formed with oppositely disposed sloping sides 122 on each forward edge thereof that are wedgingly received in the depression 78".

The device shown in Figure 7 is calibrated in exactly the same manner as the device of Figure 5. However, the structure just described permits canting of block 20 in either direction to a greater degree than is possible with the arrangement of Figure and therefore a wrench using the structure of Figure 6 can be calibrated to a greater difference of clockwise and counterclockwise breaking points.

Figures 7 and 8 show still another form of my invention that includes an arm 14' that is cylindrical in configuration, rather than rectangular as in the previously described forms of the invention. Opening into the rear end of the arm 14 is a blind axial bore 130 whose wall is inwardly dimpled as at 132. The arm 14" is thus adapted to receive the generally cylindrical stem of a buttress element 134. It will be observed that the stem 136 is flattened along one side thereof as is indicated by the numeral 138, whereby said stem is axially slidably received in the bore 130 but held against rotation therein. This arrangement permits the head 146 of the buttress element 134 to be held in the proper relationship relative to the forward face of a plunger 74 for reasons which will presently become apparent.

The rear face of the head 1140 of buttress element 134 is formed with a depression 78" that is identical inconfiguration to the depression 78 formed in the rear face of the arm 14 of the preferred embodiment of the invention shown in Figure 4. The forward face of the plunger 74" similarly is formed with a depression 86 which is identical in configuration to the depression 80 of the plunger 74 shown in Figure 4. The confronting faces of the buttress element 134 and plunger 74' are thus adapted to hold a block therebetween which is identical in shape and mole of operation to the block 20 shown in the device in Figure 4.

The use of a detachable buttress element 134 has many advantages, particularly in the manufacture of the device.

As is apparent, it is more convenient to heat treat a separate article, such as the buttress element 134, in order to harden it to the proper degree, than to attempt to harden merely one end of a longer member, such as the arm 14 of Figure 4. In the latter instance, i.e. when it is attampted to harden the rear end of face of the arm 14 of Figure 4, it is sometimes difiicult to carry on this hardening without adversely effecting the characteristics desired in the forward portions of the arm. Thus, in some cases the forward portion of the arm may become unduly hard and brittle whereupon it is subject to fracture when the device is in use. However, with the alternate structure just described the buttress element 134 can be individually hardened to the desired degree without exposing the arm 14' to any undesired heat treatment.

The alternate structure just described also has theadvantage of providing another cam adjustment means for Calibrating the wrench. As can be seen in Figure 7, one or more Washers 142 can be placed around the stem 136 of the buttress element 134 to be held between the rear end of the arm 14"' and the forward face of the head of the buttress element. With this arrangement, the desired amount of compressive force for calibration of the Wrench can be impressed on the spring means behind the plunger 74 merely by adding as many washers 142 as desired.

Adding or subtracting washers 142, aside from varying the compression of the spring means of the wrench, also changes the angle between the longitudinal centerline of the arm 14 and a line 162 between the axis of hinge pin 54 and either of the front edges of the pivot or block 20". This also acts as a cam adjustment for Calibrating the wrench.

Figures 9 and l0 show an alternate form of spring, designated by the numeral 144, that is particularly useful in large torque wrenches, as is the spring 72. Heretofore, large wrenches have employed helical springs or circular washer-type springs, which are necessarily of large diameter in order to achieve the requisite spring force. In order to reduce the cross-sectional area required for spring means of sufficient force for large torque wrenches, whereby to reduce the wrench to convenient handling size, and in order to adapt such spring means for inclusion in a small cavity of rectangular cross-section, I have devised the spring 144, whose configuration is best seen in Figure 9.

The springs 144 are made of a substantially rectangular piece of spring metal that is formed with a center web 146 that has an angularly offset arm 148 at each end thereof. The end of each arm 148 is turned outwardly in a plane parallel to that of web 146, as indicated by the numeral 150, to provide fiat bearing surfaces at each end of each spring 144. The web 146 is formed with a first transversely extending, substantially V-shaped groove 152 that is offset from web 146 in the same direction as arms 148, and with a second substantially V-shaped groove 154, parallel to first groove 152 and offset `from web 146 in the opposite direction. It is highly desirable for the springs 144 to be formed in such a way that the opposite faces thereof have identical contours so that they do not have localized areas of thinness (such as would result from a bending operation) and so that adjacent springs will couple properly in the manner shown in Figure 9 or Figure l0.

In Figure 9, the springs 144 are coupled in a series of abutting pairs thereof in a manner similar to the coupling of the springs 72 in Figure l. It will be observed that the rear face of the plunger 7 4 is formed with a V- shaped notch 156 adapted to receive the second groove 154 of the adjacent spring 144 and each pair of springs 144 is joined to the next pair by virtue of the mating engagement of the notches 152 and 154, and the plurality of springs 144 is thus locked in alignment.

Figure l0 shows another arrangement of springs 144 for use in torque wrenches having an extremely high breaking point wherein a great number of springs 144 must be confined in a small space. In this arrangement all of the springs 144 are nested together in mating engagement and the cap 76 of adjusting rod 66 carries a plate 158 adapted to provide a bearing surface for the column of springs 144.

It will be apparent that the springs 144 can also be stacked in a manner combining the arrangements of Figures 9 and 10. Thus, in Figure l0 if it is desired to multiply the space in which the springs can 4be compressed, some of the springs 144 can be reversed to form abutting pairs thereof as in Figure 9.

While the forms of the invention herein shown and described are fully capable of achieving the objects and providing the advantages hereinbefore set forth, it will 'be apparent that .various .modificationsl andchanges may be made therein withoutfdeparting from the spirit of the invention or the scope of the'following claims.

I claim: 1. A torque wrench comprising: a load engaging member; a head; ratchet and pawl means connecting said head and mernber; a lever pivotally connected to said head on the same axis as said member; an axially slidable plunger carried by said lever; spring means that constantly urge said plunger towards said head; and a camming element between said plunger and head.

A2. A torque wrench comprising: a load engaging mem aber; a lever pivotally connected to said member on the ber; a lever drivingly connected to said member on the axis of said member; a slidable plunger carried by said lever; spring means carried by said lever that yieldably urge said plunger towards said member; a lbuttress element on the rear end of said member that is formed with a rearwardly opening depression; and a camming element between said buttress element and said plunger, the forward face of said camming element being seated in said depression of said buttress element and the rear end of said element being seated in a depression formed in the forward face of said plunger.

4. A torque wrench comprising: a load engaging member; a lever pivotally connected at a point along its longitudinal centerline to said member on the axis of said member; an axially slidable plunger carried by said lever rearwardly of said member; spring means constantly urging said plunger towards said member; a camming element between said plunger and member that is normally centered on the longitudinal centerline of said lever; and means carried by said member to cant said camming element relative to said centerline.

5. A torque wrench comprising: a load engaging member; a head; ratchet and pawl means connecting said head and said member; a lever pivotally connected to said head on the same axis as said member; an axially slidable plunger carried by said lever rearwardly of said head; spring means carried by said lever for yieldably urging said plunger towards said head; a camming element between said plunger and head that is normally centered on the longitudinal center line of said lever; and calibration means carried by said head to cant said camming element relative to said centerline.

6. A torque wrench comprising: a load engaging member; a head in which said member is journaled and that includes a rearwardly extending arm over said member; ratchet and pawl means drivingly connecting said head and member; a lever pivotally connected at a point along its longitudinal center line to said arm on the same axis as said member; an axially slidable plunger carried by said lever rearwardly of said arm; spring means constantly urging said plunger towards said arm; and a camming element between said plunger and said arm that is normally centered on the longitudinal centerline of said lever, the forward end of said element being seated in a sloping sided depression formed in the rear face of said arm and the rear end of said element being seated in a sloping sided depression formed in the forward face of said plunger, with the minimum width of said depressions being substantially the same as the width of said element.

7. A torque wrench comprising: a load engaging member, a lever drivingly connected to said member; an axially slidable plunger carried by said lever rearwardly of said member; a cammin-g element between said plunger and said member; and a plurality of spring members carried by said lever constantly urging said plunger towards said member, eaoh of said spring members having a flat center section and a pair of outwardly offset vl0 -sides andbeingfarranged in abuttingrpairs, with the mem- Vbers of each pair abutting one another at'the outer ends thereof to resiliently maintain the center sections/thereof spaced apart and with said pairs abutting one 'another at said center sections.

8. A torque wrench, comprising: a load engaging member; a head in which said member is journaled; a ratchet wheel concentrically rigidly mounted on said member; a movable pawl carried by said head; manually movable means to place said pawl in a rst position in which is engages said ratchet wheel to drivey it in clockwise direction only, and a second position in which it engages said ratchet ywheel to drive it in counterclockwise direction only; means carried by said head to yieldably Vmaintain said pawl in the position to which it is manually moved; a fixed arm section rigidly mounted on said head to extend over said 'member and rearwardly therefrom;ran elongate, hollow lever of substantially rectangular cross-section that is pivotally connected at a point along'its centerline to said `fixed arm section on the same axis as said member; an `axially slidable plunger carried by said lever rearwardly of said fixed arm section; a plug affixed to the rear end of `said lever and having a centrally disposed threaded bore; la tubular handlerotatably mounted on the rear portion of said lever; an interiorly disposed, axially extending rod rigidly aixed to the rear wall of said handle that is externally threaded to engage said bore of said plug, spring 'means between said rod and said plunger that constantly urge said plunger forwardly; a camming block normally centered on the longitudinal centerline of said lever, the rear end of said block being wedgingly received in a depression formed in the forward face of said plunger; a second arm section longitudinally slidably mounted on said yfixed arm section, both of said sections defining a depression between the rear ends thereof that wedgingly receives the forward end of said block; and set screw means connecting said arm sections.

9. A wrench as set forth in claim 8 in which said spring means comprises a plurality of spring members carried by said lever constantly urging said plunger towards said member, each of said spring members having a flat center section and a pair of outwardly offset sides and being arranged in abutting pairs with the members of each pair abutting one another at the outer ends thereof to resiliently maintain the center sections thereof spaced apart and with said pairs abutting one another at said center sections.

l0. A torque wrench comprising: a load engaging member; a head that includes a rearwardly extending arm; unidirectional driving means connecting said head and member; a tubular lever of substantially rectangular crosssection pivotally connected to and loosely receiving said arm; a plunger slidably mounted in said lever rearwardly of said arm; a camming element wedgingly mounted between adjacent ends of said arm and plunger; and at least one spring between a relatively fixed abutment at the rear end of said lever and the rear end of said plunger for yieldably urging said plunger towards said arm, said spring being substantially rectangular in area and being formed with angularly offset opposite ends and the opposite faces of said spring being of identical configuration.

11. A torque wrench comprising: a load engaging member; a lever pivotally connected to a head on said member; a plunger movably mounted on said lever; means on said lever for yieldably urging said plunger towards said head; a camming element between said plunger and said head; and means for adjusting the spacing between the abutment of said element with said head and the pivotal connection of said head with said lever.

12. A torque wrench comprising: a load engaging member having a rearwardly extending arm; a lever pivotally connected to said arm; a buttress element on the rear end of said arm; cam adjustment means for varying the spacing between the pivotal connection of said arm and lever and said buttress element; a plunger movably mounted on said c 11 lever; spring means on said lever for yieldably biasing said plunger towards said head; and a camming element between said plunger and buttress element.

13. A device as set forth in claim 12 in which said buttress element includes a stem slidably mounted in a bore opening into the rear face of said arm and said cam adjustment means comprises at least one washer mounted on said stern between the rear end of said buttress element and the rear face of said arm.

14. A torque wrench, comprising: a load-engaging member; a head in which said member is journaled and that includes a rearwardly extending arm over said member; ratchet and pawl means drivingly connecting said head and member; a lever pivotally connected at a point along its longitudinal center-line to said arm on the same axis as said member; an axially slidable plunger carried by said lever rearwardly of said arm; spring means constantly urging said plunger towards said arm; a camming element between said plunger and said arm that is normally centered on the longitudinal center-line of said lever, the forward end of said element being seated in a sloping-sided depression formed in the rear face of said arm and the rear end of said element being seated in a sloping-sided depression formed in the forward face of said plunger, with the minimum width of said depressions being substantially the same as the width of said element; and calibration means carried by said arm to cant said camming element relative to the longitudinal center-line of said lever.

15. A torque wrench, comprising: a load-engaging member having a rearwardly extending arm; a lever pivotally connected to said member; and resilient means for holding said lever against angular movement relative to said member including a slidable plunger carried by said lever in axial alignment therewith, a cuboid camming element of substantially rectangular cross-section positioned between said plunger and the rear end of said arm, and spring means carried by said lever acting on said plunger urging said camming element into engagement with the rear end of said arm, with the confronting sides of said plunger and said arm being formed with sloping-sided depressions defining corners adapted to receive knife edges of said camming element.

References Cited in the le of this patent UNITED STATES PATENTS

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